In an image forming apparatus, such as a laser printer, a laser beam is swept, or scanned, across a photosensitive drum. The accurate and precise placement of the swept laser beam ensures that the resulting output from the image forming apparatus is an accurate representation of the desired image.
Manufacturing tolerances and assembly techniques have an impact on the accuracy with which the laser beam strikes the photosensitive drum. Each of the components that interact with the laser beam, including the laser, the scanner, and any lenses and mirrors, potentially affects the path of the laser beam. Accordingly, it is important to be able to align one or more of the components to ensure the precise and accurate placement of the laser beam.
The scanning element, because it reflects the laser beam and also redirects the laser beam within a scan path, is particularly susceptible to misalignment. The precise placement and positioning of the scanner in the laser scanning unit greatly aids in the accurate representation of the desired image.